The increased use of microwaves for cooking has given rise to a large market in microwavable foods. While the advantage of microwave cooking over convection oven cooking is the time savings, the disadvantage is that baked goods and meats do not develop the surface browning or crust formation expected with convection oven cooking.
Our objective has been to create that browning which enhances the products appearance, making it look as if it were cooked in a convection oven.
In the microwave, food does not have sufficient time or temperature for the chemicals responsible for browning to react. Therefore, for a microwave browning system to work, it must accelerate the rate of the browning reactions or locally increase the surface temperature. Ultimately, the reactions responsible for browning have to be accomplished in the relatively short time frame dictated by the foods preparation conditions. The times needed for preparing microwave foods vary depending upon the power output of the microwave unit and the mass of the food to be cooked. A typical 750 watt microwave will cook baked goods in 40 seconds to 4 minutes, while meat will take 6 to 15 minutes.
Several additional requirements for a successful microwave browning system are as follows:
1. in addition to the desired browning effect, it must generate either no aroma or one which is compatible with the target food.
2. the browning reaction must not take place before cooking the food.
3. after cooking, the browning must stop, and not darken substantially.
The reactions responsible for browning during convection oven cooking are the caramelization of sugars and the Maillard reaction between naturally occurring reducing sugars, amino acids, amines, peptides and proteins which results in the formation of colored melanoidins. Until recently (1984) there were numerous patent and literature references to such reactions for the production of flavors, where the generation of color was inconsequential or objectionable. In the past few years several patents have appeared wherein microwave browning created by Maillard reactions have been the topic.
Although the prior art does take advantage of the reaction between reducing sugars and amino acids, it has not made any correlation of reaction rates needed for browning reactions with reaction variables such as pH, solvent, or sugar reactivity.